Car surges and tops at about 3000rpm's

I had a bad ignition coil and replaced it as well as the spark plugs and wires. The car now is limited in it’s rpm’s. Only gets to a guestimate of 3000 RPM’s then tops out. It also surges in idle. I’m guessing due to the bad ignition coil the CAT’s insides melted and so I gutted it to see if it would run better due to back pressure but doesn’t. Could this be a O2/Cat problem or do I have a larger issue. I checked the timing as well and it is within spec’s. Don’t know where to go from here.

Help…